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As suggested by Peris,One feature of the webs of some orb-weavers is the stabilimentum, a crisscross band of silk through the center of the web. The band has been hypothesized to be a lure for prey, a marker to warn birds away from the web and a camouflage for the spider when it sits in the center of the web. However, recent research suggests that the stabilimentum actually decreases the visibility of the silk to insects, thus making it harder for prey to avoid the web.
There is much controversy surrounding the function of these structures, and it is likely that different species use it for different purposes. 1. Some people believe that they provide protection to the spider by either camouflaging it or making it appear larger. 2.Another theory is that they make the spider visible and therefore animals such as birds are less likely to damage the spider’s web. 3. Originally the decorations were thought to stabilize the web (hence the term stabilimentum)[citation needed], though this theory has since been dismissed. 4.One more recent theory is that web decorations attract prey by reflecting ultraviolet light.Light in the ultraviolet part of the spectrum is known to be attractive to many species of insects 5.Many other theories have also been proposed such as thermoregulation, stress, regulation of excess silk, or simple aesthetics. At least one variant has been observed to vibrate the web, while positioned in the stabilimentum, when approached by a body the size of a human. 6. Another theory is camouflage as it breaks up the outline of the spider. One theory has been put forward that the purpose of the stabilimentum is to attract the male of the species to the web when the female is ready to reproduce. 7. A limited study carried out in the Calahonda area of Spain in the summer of 1992 showed that there was a positive correlation between the presence of a male in the webs of Argiope lobata and the presence of a stabilimentum
Spotted on Nov 8, 2012
Submitted on Nov 15, 2012
31 Comments (1–25)
Thats an incredible thinking Lauren..I am glad to discuss with you friends...
This Saga of the Stabilimentum has been great fun. I think the diurnal spiders that build a stabilimentum and then move to the edge of the web for the night, are doing so to avoid bats. The ecolocation of a bat will hit the stabilimentum (minus spider) and warn it that there is a web there. Bats like to fly through cleared places and spiders like that too for their webs. Both win.
What an interesting thinking Perlis...Excellent ! Thats true may be...
You r a very good observer....
So this web is probably that of a ist or 2nd instar of an orb weaver spider.
Bats use sound to communicate? Maybe the web structure bounces of the sound waves and thus conveys a message to the bat that they are up against an impenetrable barrier?
Thnx for the article . it was interesting to know that different instars make different kind of webs.
Thank you for appreciation Oneng!
Hello Lauren,
During their evolutionary history, some species of spiders have changed from a nocturnal to a diurnal lifestyle, and the important change in their environment was irradiation by sunlight. Orb webs of diurnal spiders may be markedly affected by exposure to ultraviolet (UV) irradiation, whereas those of nocturnal spiders may be unaffected. The effects of UV rays on the mechanical properties, particularly the mechanical breaking energy, of the silks of diurnal and nocturnal spiders were investigated. The results provide strong support that diurnal spiders are in a more evolved stage than nocturnal spiders, so they secrete silks with an evolved mechanical resistance against UV irradiation. This study suggests a means to search for biological materials with resistance to UV rays.
So that makes why spiders evolved more diurnal..But i dont know how it solves the mystery that still web protects from Bats! May be a close observation needed during night..We may need to be nocturnal :)
wouw amazing species and fabolous pic Adi.
Thank you nexttogone..its neat indeed!
http://en.wikipedia.org/wiki/Spider_web
This is from wiki Lauren....When scientists were given the opportunity to study the webs, they discovered that the space webs were finer than normal Earth webs, and although the patterns of the web were not totally dissimilar, variations were spotted, and there was a definite difference in the characteristics of the web. Additionally, while the webs were finer overall, the space web had variations in thickness in places: some places were slightly thinner, and others slightly thicker. This was unusual, because Earth webs have been observed to have uniform thickness...
Hi Adarsha, That is so neat about the spider experiments in space under weightless conditions. Did they say if the web, when finally constructed, was similar to it's normal web structure on Earth?
The article you mentioned is also very interesting. I was especially interested to note that the authors found that Stabilimenta are built primarily by diurnal spiders and seem to serve primarily as a deterrent to bird predation. Wrecks my thought that it also served to protect them from bat predation or even just bat destruction of the web.
Now this is a neat find.
@Frazier : Yeah..ssure....
Hi Lauren and Peris : As u interested in webs, there is a research journal on stabilimentum...Kindly read it..Its very nice written....
http://psyche.entclub.org/87/87-013.html...
Moved to Arthropods :-)
Hi Peris and Lauren,
Found some amazing facts while reading about webs...
It has been observed that being in Earth's orbit has an effect on the structure of spider webs in space.Spider webs were spun in low earth orbit in 1973 aboard Skylab, involving two female European garden spiders (cross spiders) called Arabella and Anita, as part of an experiment on the Skylab 3 mission. .
After the launch on July 28, 1973, and entering Skylab, the spiders were released by astronaut Owen Garriott into a box that resembled a window frame. The spiders proceeded to construct their web while a camera took photographs and examined the spiders' behavior in a zero-gravity environment. Both spiders took a long time to adapt to their weightless existence. However, after a day, Arabella spun the first web in the experimental cage, although it was initially incomplete.
Thank you for the attention Lauren...
Thank you for appreciation Joe...
Very keen observation Peris..."Stabilientum", special word..I ll edit the name..I found that its structure satisfies "Golden ratio=1.614....
PerilsOfPlastic, your observations on web building are fascinating! I never thought to watch the same spider day after day and see what he does. Very neat.
Lauren ,I was observing orb weavers and they do plan and have a strategy.
They eat up their web strand by strand on a daily basis. The new web is then constructed depending on the observations the spider makes on the previous day.Some times I found the web to be towards the ground or sometimes higher up. The shape changed too sometimes just being a few strands,
So some thinking does stake place on the spiders part.
Hi PerilsOfPlastic, That makes sense too, that the stabilimentum serves to divert birds. After so much work to create a web, a spider would be frustrated having birds or bats (must work for bats even better) break it all apart. Everything in evolution has a reason.
Stabilimentum! Great word. Thank you for the information, I can see that maybe a flying insect would be so distracted at missing the stabilimentum that it would crash into the rest of the web.
Lauren ,this is from the wikipedia,
One feature of the webs of some orb-weavers is the stabilimentum, a crisscross band of silk through the center of the web. It is found in a number of genera, but Argiope, which includes the common garden spider of Europe as well as the yellow and banded garden spiders of North America, is a prime example. The band has been hypothesized to be a lure for prey, a marker to warn birds away from the web and a camouflage for the spider when it sits in the center of the web. However, recent research suggests that the stabilimentum actually decreases the visibility of the silk to insects, thus making it harder for prey to avoid the web.
This spotting looks like the stabilimentum of an orb weaver.
Lauren,in some other kind of webs I have read that the orb weaver makes certain parts of the web conspicuous so that birds can see the web and not fly into it.
Really neat. What could be the purpose of this kind of web structure? It is too visible to things flying around. Or a prospective prey could think it was a flower?
Yeah..Magic geometry it is...Thank you Argy..
Thank you Gilma...